1. Field of the Invention
This invention relates to abrasive articles comprising a grinding aid dispersed in a binder. The binder is comprised of a blend of thermoplastic and thermoset resins.
2. Discussion of the Art
Abrasive articles generally comprise abrasive grains secured within a binder. In a bonded abrasive, the binder serves to bond the abrasive grains together such that they form a shaped mass. Typically, this shaped mass is in the form of a wheel and thus it is commonly referred to as a grinding wheel. In coated abrasives, the binder serves to bond the abrasive grains to a substrate or backing, and the binder may be comprised of make and size coatings. In nonwoven abrasives, the binder serves to bond the abrasive grains to a lofty, open, fibrous substrate.
Abrasive binders typically comprise a glutinous or resinous adhesive, and, optionally, additional ingredients. Examples of resinous adhesives include phenolic resins, epoxy resins, urethane resins, acrylate resins and urea-formaldehyde resins. Examples of typical additives include grinding aids, fillers, wetting agents, surfactants, pigments, coupling agents, and dyes.
The addition of grinding aids may significantly affect the chemical and physical processes of abrading metals to bring about improved performance. It is believed that grinding aids either 1) decrease the friction between the abrasive grains and the workpiece being abraded, 2) prevent the abrasive grains from "capping" i.e., prevent metal particles from becoming welded to the tops of the abrasive grains, 3) decrease the interface temperature between the abrasive grains and the workpiece, or 4) decrease the required grinding force.
The abrasive industry is always evaluating means to improve the abrading efficiency of abrasive articles without unduly increasing their cost. It is desired to provide a means for utilizing a higher concentration of grinding aid in an abrasive product without significantly reducing the strength of the binder.
In recent years there has been a need to coat binder precursors exclusively from aqueous solutions or dispersions due to increasingly stringent pollution concerns. Accordingly, it is desired to provide abrasive articles having a peripheral coating comprising a grinding aid dispersed in a binder wherein the precursor of the binder can be coated from water or other aqueous compositions.